Metabox doesn't retain values

Question

I have this code in functions.php in order to have a meta box displayed in the backend. The problem is, this was functioning normally until I've moved the website from a subdomain (dev) to the root and now even if the metabox appears in the backend, it doesn't retain the values anymore.

<?php
define('MY_WORDPRESS_FOLDER',$_SERVER['DOCUMENT_ROOT']);
define('MY_THEME_FOLDER',str_replace('\\','/',dirname(__FILE__)));
define('MY_THEME_PATH','/' . substr(MY_THEME_FOLDER,stripos(MY_THEME_FOLDER,'wp-content')));

<?php
define('MY_WORDPRESS_FOLDER',$_SERVER['DOCUMENT_ROOT']);
define('MY_THEME_FOLDER',str_replace('\\','/',dirname(__FILE__)));
define('MY_THEME_PATH','/' . substr(MY_THEME_FOLDER,stripos(MY_THEME_FOLDER,'wp-content')));

add_action('admin_init','my_meta_init');

function my_meta_init()
{
    $post_id = $_GET['post'] ? $_GET['post'] : $_POST['post_ID'] ;
    if ($post_id == '2') {
    foreach (array('post','page') as $type) 
    {
        add_meta_box('my_all_meta_home', 'Additional info', 'my_meta_setup', $type, 'normal', 'high');
    }
    }
    add_action('save_post','my_meta_save');
}
function my_meta_setup()
{
    global $post;
    $meta = get_post_meta($post->ID,'_my_meta',TRUE);
    include(MY_THEME_FOLDER . '/meta.php');
    echo '<input type="hidden" name="my_meta_noncename" value="' . wp_create_nonce(__FILE__) . '" />';
}

function my_meta_save($post_id) 
{
    if (!wp_verify_nonce($_POST['my_meta_noncename'],__FILE__)) return $post_id;
    if ($_POST['post_type'] == 'page') 
    {
        if (!current_user_can('edit_page', $post_id)) return $post_id;
    } 
    $current_data = get_post_meta($post_id, '_my_meta', TRUE);  
    $new_data = $_POST['_my_meta'];
    my_meta_clean($new_data);
    if ($current_data) 
    {
        if (is_null($new_data)) delete_post_meta($post_id,'_my_meta');
        else update_post_meta($post_id,'_my_meta',$new_data);
    }
    elseif (!is_null($new_data))
    {
        add_post_meta($post_id,'_my_meta',$new_data,TRUE);
    }
    return $post_id;
}
function my_meta_clean(&$arr)
{
    if (is_array($arr))
    {
        foreach ($arr as $i => $v)
        {
            if (is_array($arr[$i])) 
            {
                my_meta_clean($arr[$i]);
                if (!count($arr[$i])) 
                {
                    unset($arr[$i]);
                }
            }
            else 
            {
                if (trim($arr[$i]) == '') 
                {
                    unset($arr[$i]);
                }
            }
        }
        if (!count($arr)) 
        {
            $arr = NULL;
        }
    }
}

Would you please help me understand what's wrong? I can't figure this out and is quite frustrating. The code is not changed at all, the output for my metabox is in another php file in the theme root, nothing is changed really.

The only thing I can think of, is that developing the website on a subdomain, when I've copied the files to the root I didn't create another database as I didn't need one and have used the one I had and then used a plugin to change all the URL's. And then I've used a plugin to search and replace URL values in the database, but this was happening before altering the database. I can't be this anyway.

When I edit the metabox in the back end, I have no error, the post/page is updated, but it's obvious the database doesn't retain the new values and after editing the fields are emtpy. Here's what I have in the meta.php:

<input type="text" name="_my_meta[title]" value="<?php if(!empty($meta['title'])) echo $meta['title']; ?>"/>
<span>Enter in a title</span>


<label>Body text</label>
<textarea name="_my_meta[body-text]" rows="5"><?php if(!empty($meta['body-text'])) echo $meta['body-text']; ?></textarea>
<span>Enter in the body text</span>


<label>Link</label>
<input type="text" name="_my_meta[link]" value="<?php if(!empty($meta['link'])) echo $meta['link']; ?>"/>
<span>Enter in the URL of the link</span>

<span>e.g. <code><a href='services/' > View our Services page < /a ></code></span>

Later edit:

This is how I get my metabox values:

<?php 
global $wp_query;
$postid = $wp_query->post->ID;
$array = get_post_meta($postid,'_my_meta',TRUE);

  echo "<h1>"; echo $array['title']; echo "</h1>"; 
  echo '<p>'; echo $array['body-text']; echo '</p>'; 
  echo $array['link']; ?>

Answer 1

Many of the comments below refer to code used for debugging, which for clarity I've removed.

I should have spotted this soon - you are adding only one row into the postmeta table, and that row has the key _my_meta. Before inserting the array int the table, WordPress serializes the array. When you retrieve the meta, you are retrieving a serialized array which you would then need to unserialize.

However, I don't think this is what you want, (nor is it advisable). It would be better to save each of the values in the array as a separate key-value pair in the database (this would be more effecient, and allowing querying of specific key-values etc).

To do that you need to loop through the received data array and add each key-value individually: (I have relaced your code with appropriate comments)

function my_meta_save($post_id) {

// verify this is not an auto save routine. 
if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) return $post_id;

//Perform nonce checks & permissions (for pages and posts)

//Sanitize the input 

//Declare a white list of 'keys' with their defaults (or null)
//- i.e. this code will not add any other keys:
$whitelist = array(
    'title'=>null,
    'img01-title'=>null,
    'img01-url'=>null
);
   //It would probably make sense to do this before sanitzing. 
    $new_data = shortcode_atts($whitelist,$new_data);

   //Now add/update or remove key-values appropriately
   foreach ($whitelist as $key=>$value){
        //If the key has a value, update it. If it doesn't already exist it will add it
        if(!is_null($whiltelist[$key]))
              update_post_meta($post_id,$key,$value);
        else
              delete_post_meta($post_id,$key);
    }

    //No need to return, this is an action not a filter
 }

Remarks

1. I've added an auto-save check so that data is updated when the post/page auto saves
2. You've checked permissions if the post is a page - you should do this for posts too.
3. I've made use of shortcode_atts which will remove any keys that you haven't declared in $whitelist. It will assign default values to keys that are missing/don't have a value.
4. update_post_meta will add a new key if it doesn't exist